Lunyu IV. 22. (88)

The virtue of the ancients seen in their slowness to speak.
The Master said, "The reason why the ancients did not readily give utterance to their words, was that they feared lest their actions should not come up to them."

Legge IV.22.

The Master said, 'In antiquity men were loath to speak. This was because they counted it shameful if their person failed to keep up with their words.'